HCL Sensor Platform for Respiratory Assist Device Patients

ABSTRACT

An HCL sensor platform for respiratory assist device patients comprising: An HCL sensor configured to be coupled to a respiratory assist device; A processer coupled to the HCL sensor and configured to detect the presence of HCL indicative of regurgitation/aspiration of the patient; and An audio visual display coupled to the processor and providing an audio and/or visual display of the aspiration of the patient.

RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationSerial Number PCT/US2019/021967, filed Mar. 13, 2019 which publishedSep. 19, 2020 as WO 2019/178175, which is incorporated herein byreference. International Patent Application Serial NumberPCT/US2019/021967 claims priority to U.S. Patent Application Ser. No.62/642,079 filed Mar. 13, 2018 titled “Method and Apparatus for PainMitigation, Apnea Detection, Aspiration Detection and PatientCommunication in Anesthesia Patients” which is incorporated herein byreference in its entirety.

BACKGROUND INFORMATION 1. Field of the Invention

The present invention relates broadly to a method and an apparatus foraspiration detection in respiratory assist device patients.

2. Background Information

Not all surgeries have to be done with general anesthesia; i.e., thetype that renders the patient unconscious. Sometimes, light sedation(usually used to supplement local numbing injections) is enough to keepthe patient comfortable. Possible options for sedation are light,moderate, or deep—depending on the situation. The continuum ofconsciousness, as relates to anesthesia, proceeds as follows: awake (nosedation); lightly sedated; moderately sedated; deeply sedated;unconscious (under general anesthesia). Further it is not alwayspossible to predict the level of sedation that will be needed by aspecific patient for a specific procedure.

Monitored anesthesia care (MAC) means that an anesthesiologist (or nurseanesthetist, anesthesia resident, anesthesiology assistant) is presentand responsible for the sedation, care, and monitoring of the patientduring the procedure. Any level of sedation can be a MAC anesthetic, andfor a MAC anesthetic, the anesthesiologist will assess the patientpreoperatively, monitor and medicate intraoperatively, and direct therecovery postoperatively.

An important aspect of MAC is communication between the patient and theanesthesiologist. As discussed in Anesthesiologists and PerioperativeCommunication, Vincent J. Kopp, M.D.; Audrey Shafer, M.D. Anesthesiology8 2000, Vol. 93, 548-555, communication between the patient and theanesthesiologist is helpful in preoperative, intraoperative, andpostoperative stages. Intraoperative communication with patients cangreatly assist the effective monitoring and medication stratagems forthe anesthesiologist and can mitigate patient pain and improve patientoutcomes.

Regurgitation and aspiration during anesthesia is a long recognizedcomplication that was first recognized as a cause of ananesthetic-related death in 1848. Aspiration is inhalation of materialinto the airway and it has been linked with a range of detrimentalclinical outcomes. See Aspiration during Monitored Anesthesia Care, JohnKyle Bohman, M.D., Anesthesiology 2 2015, Vol. 122, 471-472; Aspirationinduced by remifentanil: A double-blind, randomized, crossover study inhealthy volunteers, Savilampi, J, Ahlstrand, R, Magnuson, A, Geijer, H,Wattwil, M. ANESTHESIOLOGY. (2014). 121 52-8. Although some in the fieldhave differentiated between pharyngeal-to-pulmonary aspiration (eitheroropharyngeal or nasopharyngeal) and gastric-to-pulmonary aspirationregarding patient outcomes, it is agreed that prompt detection of allaspiration is an important aspect of MAC for improving patient outcomes.

Hypoventilation, apnea, and airway obstruction (combined herein underapnea) are also common complications encountered during proceduralsedation. Pulse oximetry, routinely used during monitored anesthesiacare (MAC)/sedation, is a reliable estimate of oxygenation; however,detection of apnea or airway obstruction, as evidenced by a decline inarterial oxygen saturation (SpO₂), can be delayed, especially whenpatients are breathing supplemental oxygen. Electrical impedancerespiratory rate monitoring is also a well-established technique formonitoring apneic episodes, but it can be technically difficult,depending on the surgical site. Also, chest wall movement can occur withairway obstruction, which is interpreted by an impedance monitor as“breathing”. Capnography, the monitoring of the concentration or partialpressure of carbon dioxide (CO₂) in the respiratory gases, has been usedto monitor apnea and airway obstruction in MAC/sedated patients asdiscussed in Capnography Accurately Detects Apnea During MonitoredAnesthesia Care, Soto, Roy G. MD; Fu, Eugene S. MD; Vila, Hector Jr. MD;Miguel, Rafael V. MD, Anesthesia & Analgesia: August 2004—Volume99—Issue 2—p 379-382.

With the desire for fast turn over times between the end of a surgeryprocedure and the start of the next procedure, many patients are beingdelivered to the recovery room with a level of anesthesia that will onlyallow them to be aroused with painful stimulation, which unfortunatelyincreases the likelihood of undetected micro-aspiration. This incombination with lack of an anesthesia provider constantly at thepatient's side in the recovery room, makes a monitoring/detection devicecritical for the reduction of morbidity and mortality.

There remains a need in the art for improving anesthesia procedures forpain mitigation, apnea detection, aspiration detection and patientcommunication in anesthesia patients and to provide amonitoring/detection device that is cost effective and can be criticalfor the reduction of morbidity and mortality in all respiratory assistdevice applications.

SUMMARY OF THE INVENTION

One aspect of the present invention relates to HCL detection inrespiratory assist devices and relates to both improving anesthesia andimproving other respiratory monitory procedures. Essentially the HCLsensor will have application where a communication platform that isassociated with some aspects of the invention is not required. Thus morebroadly stated the HCL detection aspects of present invention relates toa method and an apparatus for aspiration detection in respiratory assistdevice patients. Thus one aspect of the invention is an HCL sensorplatform for respiratory assisted patients comprising: an HCL sensorconfigured to be coupled to a respiratory assist device; a processercoupled to the HCL sensor and configured to detect the presence of HCLindicative of regurgitation/aspiration of the patient; and an audiovisual display coupled to the processor and providing an audio and/orvisual display of the aspiration of the patient.

Another aspect of the invention provides a method of aspirationdetection in respiratory assist device patients comprising the steps of:coupling an HCL sensor to a respiratory assist device of a patient;detecting the presence of HCL particles indicative of aspiration of thepatient via a processer coupled to the HCL sensor; and displayingresults for aspiration of the patient on the audio visual display.

One aspect of this invention is directed to an acoustic sensor basedmethod and apparatus for pain mitigation, apnea detection, aspirationdetection and patient communication in anesthesia patients.

One aspect of this invention may be defined as providing an acousticsensor platform for anesthesia patients comprising: An acoustic sensorconfigured to be coupled to one of a nasal cannula or face mask of theanesthesia patient; A processer coupled to the acoustic sensor andconfigured to i) Detect patient speech and isolate and amplify thepatient speech and ii) Detect at least one of a breathing rate of thepatient or aspiration of the patient; and An audio visual displaycoupled to the processor and providing an audio and/or visual display ofthe isolated and amplified speech of the patient, and displaying resultsfor at least one of a breathing rate of the patient or aspiration of thepatient.

The acoustic sensor platform for anesthesia patients according to oneembodiment of the invention can provide wherein the step of detectingpatient speech and isolating and amplifying the patient speech includesproviding real time dictation of the words of the patient to bedisplayed on the audio visual display. Additionally the invention mayprovide that the step of detecting patient speech and isolating andamplifying the patient speech includes noise cancellation to removeundesired background noise to isolate the patient's voice and amplifythis patient voice signal for the operator which isolated and amplifiedaudio signal is transmitted over the audio visual display. The acousticsensor platform for anesthesia patients according to the invention mayprovide wherein an audible and dictated textual record of the isolatedand amplified patient speech during a proceeding is automaticallycreated and stored.

The acoustic sensor platform for anesthesia patients according to oneaspect of the invention may provide wherein the platform detects abreathing rate of the patient, and wherein the detection of thebreathing rate includes apneic detection of an apneic episode. The audiovisual display may visually displays results of the breathingrate/apneic episode detection in real time and the audio visual displaymay alert the operator of dangerous or significant conditions of thepatients breathing rate. A record of the detected breathing rate duringa proceeding may be automatically created and stored.

The acoustic sensor platform for anesthesia patients according to oneaspect of the invention may provide wherein the platform detectsaspiration of the patient wherein the acoustic sensor picks up audiblesignals indicative of regurgitation/aspiration of the patient. The audiovisual display may alert the operator of dangerous or significantconditions related to regurgitation/aspiration of the patient. A recordof the detected patient aspiration during a proceeding may beautomatically created and stored.

The acoustic sensor platform for anesthesia patients according to oneaspect of the invention may further include additional physiologicsensors such as CO2 sensors, HCL sensors and temperature sensors on theplatform and coupled to the processor to supplement the acoustic sensor.

One aspect of the present invention provides a method of PainMitigation, Apnea Detection, Aspiration Detection and PatientCommunication in Anesthesia Patients comprising the steps of: Couplingan acoustic sensor configured to one of a nasal cannula or face mask ofthe anesthesia patient; Detecting patient speech and isolate and amplifythe patient speech via a processer coupled to the acoustic sensor;Detecting at least one of a breathing rate of the patient or aspirationof the patient via a processer coupled to the acoustic sensor; providingan audio and/or visual display of the isolated and amplified speech ofthe patient on an audio visual display coupled to the processor; anddisplaying results for at least one of a breathing rate of the patientor aspiration of the patient on the audio visual display.

The features that characterize the present invention are pointed outwith particularity in the claims which are part of this disclosure.These and other features of the invention, its operating advantages andthe specific objects obtained by its use will be more fully understoodfrom the following detailed description in connection with the attachedfigures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A is a schematic view of an acoustic sensor based apparatus forpain mitigation, apnea detection, aspiration detection and patientcommunication in anesthesia patients according to one embodiment of thepresent invention;

FIG. 1B is a schematic view of an acoustic sensor based apparatus forpain mitigation, apnea detection, aspiration detection and patientcommunication in anesthesia patients according to another embodiment ofthe present invention;

FIG. 2 is a schematic view of the acoustic sensor based apparatus ofFIGS. 1A and B and associated signal processing.

FIG. 3A is a schematic view of an HCL sensor based apparatus forrespiratory assist device patients according to one embodiment of thepresent invention;

FIG. 3B is a schematic view of an HCL sensor based apparatus forrespiratory assist device patients according to another embodiment ofthe present invention; and

FIG. 4 is a schematic view of the HCL sensor based apparatus of FIGS. 3Aand 3B and associated signal processing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Acoustic Sensor Platform

One aspect of the present invention relates to an acoustic sensorplatform based method and apparatus 100 for pain mitigation, apneadetection, aspiration detection and patient communication in anesthesiapatients. FIG. 1A is a schematic view of an acoustic sensor basedapparatus 100 according to one embodiment of the present invention inwhich the acoustic sensor 10 is coupled to a nasal cannula 12 of ananesthesia patient in a position adjacent the nasal passages of thepatient. As described in FIG. 3, the acoustic sensor 10 forms aBluetooth enabled patient communication platform and physiologic monitorplatform for communication with, and selective physiologic parametermonitoring of, the patient. The sensor 10 is wirelessly connected 16,via Bluetooth or other wireless coupling, to a display device 20 of theoperator (anesthesiologist).

The display 20 of the operator is a personal computer (PC) and generallya tablet or a smartphone. A tablet computer, commonly shortened totablet, is a portable PC, typically with a mobile operating system andLCD touchscreen display processing circuitry, and a rechargeable batteryin a single thin, flat package. Tablets, being computers, do what otherPC do, but often lack some input/output (I/O) capabilities that othershave. Modern tablets largely resemble modern smartphones, the onlydifferences being that tablets are often larger than smartphones and maynot support access to a cellular network. A smartphone is essentially ahandheld PC with a mobile operating system and an integrated mobilebroadband cellular network connection for voice, SMS, and Internet datacommunication; and essentially all smartphones also support Wi-Fi. Atablet and smartphone forming the device 20 have the necessary audioinputs/outputs to form the communications platform of the presentinvention and the video display for other aspects of the monitoringsystem of apparatus or platform 100.

The wireless connection 16 is used to describe a telecommunicationsprotocol that uses electromagnetic waves, rather than a hard wireconnection, for transmitting signals of interest. Bluetooth technology,represented schematically by the Bluetooth transmitter 22 in FIG. 2, isthe preferred wireless method and defines an effective standardshort-range protocol for coupling electronic devices.

FIG. 1B is a schematic view of an acoustic sensor based apparatus 100according to another embodiment of the present invention in which theacoustic sensor 10 is coupled to a mask 14 of an anesthesia patient in aposition adjacent the vents of the mask 14 of the patient. The maindifference between the embodiment of FIGS. 1A and 1B is that one isconfigured to couple the sensor 10 to a conventional nasal cannula whilethe other is constructed to couple the sensor to a mask 14. Outside ofthis difference the operation of the two embodiments will besubstantially identical.

FIG. 2 schematically outlines the associated signal processing for thethe acoustic sensor based apparatus 100 of FIGS. 1A and B. The sensor 10includes Bluetooth technology, shown by transmitter/receiver 22, forforming the wireless coupling 16 with the processor 30 in the display20. The processor 30 could be removed from the display 20 and housed ina separate device that is coupled to the display 20, even possibly becloud based, but the display 20 is generally preferable as it avoidscommunication interruptions of lags.

The sensor 10 includes an acoustic sensor or microphone 24 for obtainingthe audible inputs from the patient. A microphone 24 broadly is atransducer that converts sound into an electrical signal. Microphonesare often categorized by the specific method used to convert the airpressure variations of a sound wave to an electrical signal. The mostcommon microphone is a dynamic microphone, which uses a coil of wiresuspended in a magnetic field; a condenser microphone, which uses thevibrating diaphragm as a capacitor plate, and the piezoelectricmicrophone, which uses a crystal of piezoelectric material. Anymicrophone type can be used as acoustic sensor 24 provided it is compactand is sufficient to pick up the patient's audible and physiologicsignals.

In addition to the microphone or audible or acoustic sensor 24 thesensor 10 includes a CO₂ sensor 26 sufficient for capnography, namelythe monitoring of the concentration or partial pressure of carbondioxide (CO₂). See for example CO2 sensors from E+E Elektronik,SenseAir'sK30 10,000 ppm CO2 sensor, and the SprintlR6S 5% CO2 Sensor(which is capable of measuring CO2 levels up to 20 times per second).

The sensor 10 may optionally include a hydrochloric acid (HCL) sensor 28for measuring HCL concentrations of select samples. HCl is the primaryacid found in the stomach, and thus the HCL sensor 28 can be helpful fordetecting regurgitation of the patient relevant for aspirationdetection. Regarding acceptable HCL selection sensor, Detcon ModelDM-700-HCL from 3M is a HCL sensor designed to detect and monitorHydrogen Chloride in air over the range of 0-30 ppm usingelectrochemical sensor technology. Mil-ram technology, Inc.'s Tox-Array2102 sensor detects HCL at 0.0 to 20.0 ppm along with other gasses.MSA's TS4000H sensor detects HCL at 0.0 to 20.0 ppm along with othergasses. Global Detection Systems Corp.'s GDS-49 sensor detects HCL at0.0 to 30.0 ppm along with other gasses. Other sensor technology may beimplemented for HCL detection such as photoplethysmography sensingtechnology utilized for HCL detection based upon HCL light absorption.

The sensor 10 can accommodate other physiologic parameter sensors 25 asdesired, such as a temperature sensor, PH sensor or other desiredsensor.

The signal processor 30 is preferably an artificial intelligence basedor artificial neural network based signal processing system forprocessing the acoustic signals from sensor 24 in a patient operatorcommunication platform 32, a breathing rate/apneic detection monitor 34,and a regurgitation/aspiration detection monitor 36 as discussed below.The artificial intelligence based or artificial neural network basedsignal processor 30 is intended to mean that the processor is expectedto be adaptive and learn as it moves forward to improve the results. Thespecifics and operations of such systems are known in the art.

The communication platform 32 signal processing is effectively using themicrophone 24 to pick up the speech or voice of the patient and isolateand amplify this signal so the operator can more easily hear and orreceive the spoken words or speech sounds of the patient though thedisplay device 20. The speech sounds of the patient are distinguishedherein from the other physiologic sounds of the patient related tobreathing and aspiration. The speech is likely to be mostly verbal, butgrunting and other nonverbal vocal sounds are considered herein asspeech.

One method of isolation and amplification is to provide real timedictation of the words of the patient to the audio visual display 20.The operator reading the spoken words on display 20 substantiallysimultaneously with hearing the patient can effectively “isolate andamplify” the voice signal sufficiently for the operator

Preferably, the processing 30 also uses noise cancellation to removeundesired background noise to isolate the patient's voice and amplifythis patient voice signal for the operator which isolated and amplifiedaudio signal can be transmitted over the display 20.

In the medical fields, MRI sound systems and the associated signalprocessing form a basis for this aspect of the system or apparatus 100.Capturing the voice of the patient in the present environment isconsidered easier than in the much noisier MRI field, although the voiceof the patient here may be more subtle due to the sedation level.

The microphone 24 and the communication platform (via 32) of theapparatus 100 allow the patient to more easily communicate with theanesthesiologist. Improved communication is believed to allow forsubstantial pain mitigation. Even if the audible patient speech soundsare non-verbal (e.g., grunts), this input to the anesthesiologist canimprove the patient monitoring. The communication via the device 20 alsoallows an audible, and/or dictated textual record of the proceeding tobe automatically created and stored. The invention provides that anaudible, and/or dictated textual record of the isolated and amplifiedpatient speech during a proceeding is automatically created and stored.The use of a dictated display and a simultaneous auditory display ofpatient sounds can further enhance communication. For example where thedoctor was not exactly sure of what he heard over the speaker of device20, the text display of the same patient comments can clarify this forthe doctor. Alternatively is the dictation is slightly off, the hearingof the patient's own voice can assist the doctor in clarifying what wasactually said by the patient. Thus the use of both an auditory outputand a textual output are believed to improve communications byreinforcing, cross-checking and supplementing each other,

The breathing rate/apneic episode detection 34 signal processing iseffectively using the microphone 24 to pick up the audible signalsindicative of breathing of the patient. The apneic detection is usingthis rate detector to determine when breathing rate is low or 0 for anapneic episode. Using audible sensor(s) for tracking breathing rates ofa patient, alone, is known and is sometimes called respiratory acousticmonitoring. See Performance of Masimo Rainbow Acoustic Monitoring forTracking Changing Respiratory Rates Under Laryngeal Mask Airway GeneralAnesthesia for Surgical Procedures in the Operating Room: A ProspectiveObservational Study, Atkins, Joshua H. MD, PhD; Mandel, Jeff E. MD, MSAnesthesia & Analgesia: December 2014—Volume 119—Issue 6—p 1307-1314.See also the Masimo Pulse CO-Oximeter (Masimo Corporation, Irvine,Calif.) with acoustic monitoring technology that measures respiratoryrate based on analysis of acoustic signals generated across the upperairway during turbulent flow with breathing and has been compared withcapnography for accuracy. See also the Acoustic Sleep Apnea Detectordeveloped by Vanderbilt University 2010 in which it was found that atracheal breath sound has a characteristic frequency between 400 and 700Hz and the collected sound waves were analyzed to detect a breath bycomparing the frequency content of the wave with this frequency range.

It has been known that accurate monitoring of respiratory rate may beuseful for the early detection of patient deterioration. Respiratoryacoustic monitoring for respiratory rate monitoring has beendemonstrated to provide accurate respiratory rates in patientsrecovering from anesthesia.

Where the CO2 monitor 26 is present this result can be combined with theaudible inputs for calculating and displaying the breath rate/apneicepisodes. It is envisioned that the display 20 can visually display theresults of this breathing rate/apneic episode detection 34 signalprocessing in real time and visually and/or audibly alert the operatorof dangerous or significant conditions. The display 20 allows for aneasy record of the entire session to be maintained as well, specificallythe display signals are recorded for a session whereby a record of thedetected breathing rate and/or apneic episodes detected during aproceeding is automatically created and store.

The regurgitation/aspiration detection monitor 36 signal processing iseffectively using the microphone 24 to pick up the audible signalsindicative of regurgitation/aspiration of the patient. Predictivemodeling may be implemented identifying for changes in respiration rate,pattern, etc as well as audible clues which would help to alert fordepth of anesthesia and the patients ability to protect his/her airwaye.g. passive reflux related to laxity in lower esophageal sphinctertone. Again the other sensors, namely the HCL sensor 28 can supplementthis monitor result. The display 20 can visually display the results ofthis regurgitation/aspiration detection monitor 36 signal processing inreal time and visually and/or audibly alert the operator of dangerous orsignificant conditions related to regurgitation/aspiration of thepatient. The acoustic sensor platform for anesthesia patients accordingto the invention provides that a record of the detected patientaspiration during a proceeding is automatically created and stored. Thedisplay allows for an easy record of the entire session to be maintainedas well.

HCL Sensor Platform

The HCL detection aspects of present invention alone provide broaderapplications than only when coupled to the communications platform ofthe acoustic sensor described above. Effective and efficient HCLdetection alone will improve anesthesia and other respiratory monitoryprocedures. A cost effective and efficient HCL detection platform isanother aspect of the present invention that provides an improved methodand an apparatus for aspiration detection in all respiratory assistdevice patients. Respiratory assist devices includes the nasal cannulaand mask shown above and also includes CPAP devices, Bipap devices andendotracheal tubes.

FIG. 3A is a schematic view of an HCL sensor based apparatus accordingto one embodiment of the present invention in which the HCL sensor 28′is coupled to a nasal cannula 12 of a patient which may be an anesthesiapatient, in a position adjacent the nasal passages of the patient. TheHCL sensor 28′ forms a Bluetooth enabled physiologic parametermonitoring of the patient, namely a cost effective platform formonitoring HCL particles indicative of regurgitation/aspiration episodesof the patient. The sensor 28′ is wirelessly connected via Bluetooth orother wireless coupling to a display device 20 of the operator, whichmay be an anesthesiologist or monitoring nurse or the like.

The display 20 of the operator may be a personal computer (PC) such as atablet or a smartphone, as discussed above. In this embodiment thedisplay may be a monitor at the nurse's station and may be coupled toother sensors, like a patient's pulse-Ox sensor. Thus the display 20 maybe a Pulse-Ox display that further includes a portion displaying the HCLsensor 28′ outputs (following proper processing)

FIG. 3B is a schematic view of an HCL sensor based apparatus accordingto another embodiment of the present invention in which the HCL sensor28′ is coupled to a mask 14 of a patient, which may be an anesthesiapatient, in a position adjacent the vents of the mask 14 of the patient.The main difference between the embodiment of FIGS. 3A and 3B is thatone is configured to couple the sensor 28′ to a conventional nasalcannula while the other is constructed to couple the sensor 28′ to amask 14. Outside of this difference the operation of the two embodimentswill be substantially identical. These are shown to illustrate the HCLsensor 28′ may be easily coupled to any respiratory assist device namelynasal cannula, mask, CPAP devices, Bipap devices and endotracheal tubes.

FIG. 4 schematically outlines the associated signal processing for theHCL sensor based apparatus of FIGS. 3A and B. The sensor 28′ includesBluetooth technology, shown by transmitter/receiver 22, for forming thewireless coupling 16 with the processor 30 associated with the display20. The processor 30 could be removed from the display 20 and housed ina separate device that is coupled to the display 20, even possibly becloud based, but the display 20 is generally preferable as it avoidscommunication interruptions of lags.

The sensor 28′ is a hydrochloric acid (HCL) sensor 28 for measuring HCLconcentrations of select samples. HCl is the primary acid found in thestomach, and thus the HCL sensor 28 is used for detecting regurgitationof the patient relevant for aspiration detection.

Regarding acceptable HCL selection sensor, Detcon Model DM-700-HCL from3M is a HCL sensor designed to detect and monitor Hydrogen Chloride inair over the range of 0-30 ppm using electrochemical sensor technology.Mil-ram technology, Inc.'s Tox-Array 2102 sensor detects HCL at 0.0 to20.0 ppm along with other gasses. MSA's TS4000H sensor detects HCL at0.0 to 20.0 ppm along with other gasses. Global Detection SystemsCorp.'s GDS-49 sensor detects HCL at 0.0 to 30.0 ppm along with othergasses.

A chemical reactive sensor may form the HCL sensor if the reaction isfast enough and sensitive enough. For example, rhodamine hydrazineprobes on filter paper can react to volatile vapors colorimetricallywhich change in color can be used to signal the processor. Adisadvantage is that the probes must be in contact with the breathstream directly and the sensor must further include features tocommunicate the color change to the system, and this generally requiresa second optical sensor monitoring the color.

One preferred HCL detection method of sensor 28′ is photoplethysmographysensing technology utilized for HCL detection based upon detecting HCLlight absorption. Currently Photoplethysmography (PPG) is best known inPulse-Ox application where it is a simple and low-cost non-invasiveoptical technique used to detect blood volume changes and oxygenationslevel in blood. In a conventional Pulse-Ox PPG the noninvasive sensorilluminates the skin with the light from one or two light emittingdiode(s) and then measures the amount of light either transmitted(trans-missive type PPG) or reflected (Reflective type PPG) to acorresponding photodiode. Two wavelengths of light are often usedbecause the difference in oxygen absorption at the two designatedwavelengths allows for calculation of blood oxygenation amounts.

The preferred HCL detection method of sensor 28′ is to utilizetrans-missive rather than reflective PPG detection as it is not ontissue but is being transmitted through the patients exhaled breathe inthe respiratory assist device. Further the preferred HCL detectionmethod of sensor 28′ is to utilize wavelengths of light, possiblyinfrared light, that have greater difference in HCL absorption ratessuch that the difference in light received by the photodiode for eachwavelength is indicative of the presence of HCL particles. It is alsopossible that only a single wavelength of light, such as infrared light,may be used for the HCL detection where the wavelength is essentiallyhighly absorbable by HCL such that a change in the amount of detectedlight can be used as the indication of HCL particles for the system.

A optical sensor based HCL detector 28′, with one pair or two pairs oftransmitters and receivers, offers a number of advantages over other HCLsensors. This type of sensor can be used in very small volume quantitiesand is easily capable of mounting on various intubation apparatus withno significant concern or issues. The emitter and receiver pairs aresimply mounted in a position across from each other with the sample ofinterest being positioned there between—such as on the tubing. Thesensors can easily be utilized through transparent portions of therespiratory assist devices making implementation simple. The signalprocessing is also generally well known in the pulse ox field with thedifference here being the targeting of HCL detection and absorptionrather than oxygen concentration detention. Pulse Ox signal processinghas demonstrated that highly accurate reading are attainable withminimal signal of interest (high noise to signal ratios). The opticalsensor type also has the advantage of being cost effective andnon-invasive.

The above Pulse-Ox technique adapted for HCL detection may becategorized and described as non-dispersive infrared (NDIR) where thetransmission is being measured at two wavelength regions, one atabsorbing and the other at non-absorbing wavelengths. Other opticalbased HCL sensor techniques may be utilized in this design, such asFourier transform infrared (FTIR), differential optical absorptionspectroscopy (DOAS), laser-induced fluorescence (LIF) and tuneable diodelaser absorption spectroscopy (TDLAS). Diode laser spectroscopy useshigh-frequency wavelength modulation spectroscopy with second-harmonicdetection. There are a number of technical possibilities for the sensor28′ but a non-invasive optical bases sensor is preferred.

The sensor 28′ can accommodate other physiologic parameter sensors 25 oracoustic sensor 10 or CO2 sensor as generally described above inconnection with FIGS. 1-2, however the embodiments of FIGS. 3-4 suggestthe broader application of an HCL only sensor as shown. With only an HCLsensor the cost of the system can be very effective and efficient.

The signal processor 30 is, again, preferably an artificial intelligencebased or artificial neural network based signal processing system forprocessing the HCL signals from sensor 28′. The artificial intelligencebased or artificial neural network based signal processor 30 is intendedto mean that the processor is expected to be adaptive and learn as itmoves forward to improve the results.

The regurgitation/aspiration detection monitor 36 signal processing iseffectively using the sensor 28′ signals showing the presence of HCLparticles which are indicative of regurgitation/aspiration of thepatient. The display 20 can visually display the results of thisregurgitation/aspiration detection monitor 36 signal processing in realtime and visually and/or audibly alert the operator of dangerous orsignificant conditions related to regurgitation/aspiration of thepatient. The acoustic sensor platform for anesthesia patients accordingto the invention provides that a record of the detected patientaspiration during a proceeding is automatically created and stored. Thedisplay allows for an easy record of the entire session to be maintainedas well.

The optical based HCL detection system of FIGS. 3-4 may tie into aconventional Pulse Ox monitor as the display 20. As noted above, withthe desire for fast turn over times between surgery end and start ofnext case, many patients are being delivered to the recovery room with alevel of anesthesia that will only allow them to be aroused with painfulstimulation, which unfortunately increases the likelihood of undetectedmicro-aspiration. This in combination with lack of an anesthesiaprovider constantly at the patient's side in the recovery room, makesthe present HCL monitoring/detection device critical for the reductionof morbidity and mortality.

While the invention has been shown in several particular embodiments itshould be clear that various modifications may be made to the presentinvention without departing from the spirit and scope thereof. The scopeof the present invention is defined by the appended claims andequivalents thereto.

What is claimed is:
 1. An HCL sensor platform for respiratory assistdevice patients comprising: a) An HCL sensor configured to be coupled toa respiratory assist device; b) A processer coupled to the HCL sensorand configured to detect the presence of HCL indicative ofregurgitation/aspiration of the patient; c) An audio visual displaycoupled to the processor and providing an audio and/or visual display ofthe aspiration of the patient.
 2. The HCL sensor platform forrespiratory assist device patients according to claim 1 wherein theaudio visual display alerts the operator of dangerous or significantconditions related to regurgitation/aspiration of the patient.
 3. TheHCL sensor platform for respiratory assist device patients according toclaim 1 wherein a record of the detected patient aspiration during aproceeding is automatically created and stored.
 4. The HCL sensorplatform for respiratory assist device patients according to claim 1wherein the respiratory assist device is one of a nasal cannula, facemask, CPAP device, BiPAP device or endotracheal tube.
 5. The HCL sensorplatform for respiratory assist device patients according to claim 1wherein the display is part of a Pulse-Ox display device.
 6. The HCLsensor platform for respiratory assist device patients according toclaim 1 wherein the HCL sensor is an optical sensor.
 7. The HCL sensorplatform for respiratory assist device patients according to claim 6wherein the optical HCL sensor utilizes at least one transmitter and onedetector.
 8. The HCL sensor platform for respiratory assist devicepatients according to claim 7 wherein optical HCL sensor istrans-missive.
 9. The HCL sensor platform for respiratory assist devicepatients according to claim 8 wherein optical HCL sensor relies upon thelight absorption of HCL for detection of HCL.
 10. The HCL sensorplatform for respiratory assist device patients according to claim 1,wherein the HCL sensor is a chemical reactive sensor in contact with thepatient's breath stream and configured to change color in the presenceof HCL in the patient's breath stream.
 11. A method of AspirationDetection in Respiratory Assist Device Patients comprising the steps of:a) Coupling an HCL sensor to one of a respiratory assist device of apatient; b) Detecting the presence of HCL particles indicative ofaspiration of the patient via a processer coupled to the HCL sensor; andc) Displaying results for aspiration of the patient.
 12. The method ofAspiration Detection in Respiratory Assist Device Patients according toclaim 11 wherein the HCL sensor is one of i) an optical sensor, and ii)a chemical reactive sensor in contact with the patient's breath streamand configured to change color in the presence of HCL in the patient'sbreath stream.
 13. The method of Aspiration Detection in RespiratoryAssist Device Patients according to claim 11 wherein the optical HCLsensor is a chemical reactive sensor in contact with the patient'sbreath stream and configured to change color in the presence of HCL inthe patient's breath stream.
 14. The method of Aspiration Detection inRespiratory Assist Device Patients according to claim 11 wherein thepatient is an anesthesia patient.
 15. The method of Aspiration Detectionin Respiratory Assist Device Patients according to claim 11 wherein therespiratory assist device is one of a nasal cannula, face mask, CPAPdevice, BiPAP device or endotracheal tube.
 16. An HCL sensor platformfor respiratory assist device patients comprising an HCL sensorconfigured to be coupled to a respiratory assist device, wherein the HCLsensor is one of i) a chemical reactive sensor in contact with thepatient's breath stream and configured to change color in the presenceof HCL in the patient's breath stream, and ii) an optical sensor,wherein the optical HCL sensor utilizes at least one transmitter and onedetector, and wherein optical HCL sensor is trans-missive and reliesupon the light absorption of HCL for detection of HCL.
 17. The HCLsensor platform according to claim 16 further including an audio visualdisplay and wherein the audio visual display alerts the operator ofdangerous or significant conditions related to regurgitation/aspirationof the patient.
 18. The HCL sensor platform for anesthesia patientsaccording to claim 16 wherein a record of the detected patientaspiration during a proceeding is automatically created and stored. 19.The HCL sensor platform for anesthesia patients according to claim 16wherein the respiratory assist device is one of a nasal cannula, facemask, CPAP device, BiPAP device or endotracheal tube.
 20. The HCL sensorplatform for anesthesia patients according to claim 16 wherein the HCLsensor is a chemical reactive sensor in contact with the patient'sbreath stream and configured to change color in the presence of HCL inthe patient's breath stream.